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The work is devoted to the tasks of safe operation of nuclear power plants, namely the prevention of inert radioactive gases, iodine, and its compounds from entering the air. The latter is particularly dangerous because it can accumulate in the human body. One of the methods of air purification is the use of air filters filled with activated carbon granules that have undergone preliminary treatment of thermal expansion and impregnation. At the same time, there is a problem with evaluating the change in local aerodynamic resistance as a result of the shape change of granules and their compaction when activated carbon is filled into the filter. For this purpose, the model that calculates the spatial field of movement of ventilation gases through a chamber that simulates an adsorber of the AU-1500 type filled with carbon granules was created. To verify the model, it was necessary to develop approaches to the assessment of the topology of the intergranular space and to draw up ideas about the possible inhomogeneities of such topology due to inhomogeneities in the compaction of granules during backfilling and vibration effects during operation. Therefore, an experimental model based on the assumption that air passage channels are spatially contiguous with electric current passage channels if a potential difference is applied to the "input-output" sections was proposed. Clusters of areas with heterogeneous packing by measuring the temperature distribution, which is released in the form of Joule heat were identified. Correlations between the characteristics of the spread of temperature fields and modes of current trans-mission have been established. It is shown that the obtained experimental data correlate with theoretical calculations of the flow of ventilation gases. The created set of methods allows optimization of the aerodynamic characteristics of the filter to improve their functional properties.

A wide range of drying parameters and methods are used by industry to produce dried apples. To ensure end-product safety and regulatory compliance, it is essential to evaluate the effectiveness of such industrial practices on microbial inactivation. Therefore, the objective of this study was to evaluate the effects of drying air temperature and velocity on Listeria monocytogenes inactivation during drying of apple slices. Apples (cv. Gala) were cored, sliced as rings (∼6 mm thick), and surface-inoculated with broth-grown culture of an 8-strain cocktail of L. monocytogenes to achieve an inoculation level of 8.6 ± 0.3 log CFU/g. Apple rings were dried in batches using dry air in a pilot-scale impingement oven at 60 or 80 °C air temperature and 0.7 or 2.1 m/s air velocity, and sampled every 30 min for bacterial enumeration, water activity (aw), and moisture content analysis. L. monocytogenes reduction increased (P

The paper presents the results of research on the kinetics of the binding process of self-hardening moulding sands with an organic binder under conditions of forced air flow at various pressure values. Three moulding sands made using urea-furfuryl resin Furanol FR75A technology were studied. The moulding sands were prepared on a base of quartz sand with an average grain size of dL = 0.25, 0.29 and and 0.37 mm , with permeability values of 306 , 391 and and 476 m 2/10 8Pa ∙ s (for ρ0 = 1.60 , 1.60 and and 1.61 g/cm 3, respectively). The research was conducted for a resin content of 1% with a constant proportion of hardener to resin, which was equal to 50%. Samples of the tested moulding sands were blown with air at pressures of 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 bar. The kinetics of the hardening process was monitored using ultrasound technology, according to a previously developed methodology [1]. The research was carried out on an ultrasound testing station equipped with a temperature chamber and an airflow reducer. The tests were conducted at a temperature of 20°C, and of the air flow pressure on the changes in ultrasonic wave velocity in the hardening mouldins sand as a function of time, the kinetics of the hardening process, and the degree of moulding sand hardening were determined. Additionally, the influence of the moulding sand permeability on the course of the hardening process at a constant air flow pressure was determined.

Compressible flow models are commonly used for describing air flow through pneumatic valves. Because of the difficulties in predicting viscous losses, these models ultimately rely on experimental determination of coefficients. Different equations have been proposed for different fluid speeds, having the sonic fluid velocity as a reference mark. However, one might question whether a much simpler approach, where the fluid is considered as incompressible, would still give good results within the typical range of industrial applications. Moreover, practically all models presuppose that the valve output pressure decreases in time, as in a discharge process. This paper reviews some representative one-dimensional compressible flow models and discusses the appropriateness of using equations based solely on discharging flows. Two experimental circuits, where an air reservoir is pressurized and, subsequently, decompressed, are used for comparison between different flow models. It is shown that a simpler set of equations still produces acceptable results for practical pneumatic applications.

Despite considerable differences in local conditions, the average air flow parameters at coastal stations had similar seasonal and interannual patterns. The decreasing trends in average wind speeds were not reliable due to inhomogeneity in the long-term series. Being less sensitive to inhomogeneities, both the zonal and meridional components and the average air flow estimates increased in 1966â2021. The changes in flow direction and in other wind characteristics were better described as quasi-cyclic rather than using a linear trend. In the Sõrve coastal case study, the wind velocity components were separated into opposite subsets, which were one-sidedly analysed by ignoring the other direction. Both westerly and easterly sub-components increased by 0.5 m/s in 2004â2021. Regarding wind-driven coastal processes along the peninsula, the changes in the westerly component, but not in the easterly component, are important on the western coast, and vice versa for the eastern coast. Assuming the potential impacts of winds via waves and currents, the influence of long-term changes in sea ice conditions were considered. Although the forcing load was more than twice as high on the western coast, the relative effect of the âice maskâ was smaller, as ice conditions were milder there. Along the eastern coast of the Sõrve Peninsula, the prevalence of SW-directed forcing can be expected, because the westerly forcing is shaded there by land. The SW-directed flow has strengthened over the study period because of an increase in the easterly and northerly wind speed subset and a decrease in the ice cover on the Gulf of Riga.

Unsteady gas-dynamic phenomena in pipelines of complex configuration are widespread in heat exchange and power equipment. Therefore, studying the heat transfer level of pulsating air flows in round and triangular pipes with different turbulence intensities is a relevant and significant task for the development of science and technology. The studies were conducted on a laboratory stand based on the thermal anemometry method and an automated system for collecting and processing experimental data. Rectilinear round and triangular pipes with identical cross-sectional areas were used in the work. Flow pulsations from 3 to 15.8 Hz were generated by means of a rotating flap. The turbulence intensity (TI) of the pulsating flows varied from 0.03 to 0.15 by installing stationary flat turbulators. The working medium was air with a temperature of 22 ± 1 °C moving at a speed from 5 to 75 m/s. It was established that the presence of gas-dynamic unsteadiness leads to an increase in the TI by 47–72% in a round pipe and by 36–86% in a triangular pipe. The presence of gas-dynamic unsteadiness causes a heat transfer intensification in a round pipe by 26–35.5% and by 24–36% in a triangular pipe. It was shown that a significant increase in the TI of pulsating flows leads to an increase in the heat transfer coefficient by 11–16% in a round pipe and a decrease in the heat transfer coefficient by 7–24% in a triangular pipe. The obtained results can be used in the design of heat exchangers and gas exchange systems in power machines, as well as in the creation of devices and apparatuses of pulse action.

Air permeability is used to characterize textile fabrics with respect to their usability as a garment or filter, airbag or parachute. It depends on the fabric’s porosity, air voids in the fabric, yarn specifications, thickness and other parameters, making it hard to calculate it reliably from other parameters. At the same time, measuring air permeability requires relatively expensive and complex equipment that cannot simply be built by everybody. Here, we suggest a simple device, which can be built from inexpensive components and correlates air permeability to a time measurement. We show that these values are highly correlated with the results gained by the frequently used standard EN ISO 9237.

The aim of the research is to determine ways to improve the efficiency of grain materials pneumatic separation based on the study of the interaction mechanism of grains with the air flow in the channel elements, which are inclined sections of the air duct. The paper considers a modified separation method that separates the grain material according to the aerodynamic properties of the components in a vertical zigzag air channel in an aerodynamic and gravitational field. The studies were carried out by means of mathematical modeling followed by experimental confirmation of the modeling results. A computer mathematical model was created in the MathCad 13 application package to determine the parameters of the zigzag aspiration channel. This model describes the influx of parameters in the channel (width, height, cut of the zigzag ledge to the horizon, edge of the zigzag ledge) on the nature of the grain trajectory. As a result of the numerical simulation process using the mathematical package Mathematica, dependence was obtained to determine the trajectory of motion depending on the angular velocity. An increase in the pneumatic separation effect during the grain mixtures division due to the influence of the Magnus effect was established as a result of experimental studies. The design of a zigzag separator with an annular channel section has been improved based of the research carried out.

Working conditions, in terms of hygiene, harmful impurities in the air of the working area, often do not meet regulatory requirements. In such cases, motorized filter respirators are used to protect respiratory organs, which require the development of an appropriate system for managing operational indicators for effective operation. The purpose of the article was to improve the control system of a motorized filter respirator to increase protective efficiency, due to the development of a new parametric scheme of the control object, taking into account the functional relationships between the operating mode, air flow, filter resistance and the term of protective action. To create an appropriate control system, a structural-parametric synthesis of operational indicators management was applied, based on the relationships between the main variables (outgoing regulated variables, controlling influences and disturbances). A new working diagram of the control object with selected design elements of the blower has been developed, the main difference of which is the use of the “Arduino Uno R3” board, the “LCD Keypad Shield” module with a two-line display for controlling the air flow modes, in accordance with the change of the filter resistance taking into account the accumulation dust deposit based on the assumption that the transfer function can be represented by an aperiodic link of the 1st order with sufficient accuracy for practice. To work out the operating modes and determine the duration of the protective effect, a software model of the operation of the motorized filter respirator was created, which made it possible to evaluate the influence of the dust concentration on the change in air flow through the filter elements, taking into account the accumulation of dust sediment on the protective effectiveness. Recommendations have been developed to ensure the effective functioning of the protective device in accordance with the requirements under the most unfavorable conditions. The practical value of the work lies in the fact that the modes of movement of the air flow are determined, in accordance with the speed of rotation of the fan blade from the width of the PWM pulses, which depend on the resistance of the filter, the accumulation of dust deposits based on the transfer function

Agricultural commodity drying technology aims to maintain and improve the quality of agricultural products. Coffee quality is important for the welfare of coffee farmers, and drying technology plays an important role in determining the quality of coffee. Various drying models can be applied, including the traditional model that is still applied today: drying directly under solar radiation. One drying technology that can accelerate the drying time is varying the air velocity in the drying chamber. In this study, the air velocity was varied by 1–3 m/s over coffee bean samples with an initial weight of 1500 g that were dried in parallel simultaneously. The time required was 25 h, with a maximum radiation of 586.9 w/m2 and total solar energy over 3 days of 16.6 MJ/m2. It was found that good quality coffee was achieved using drying box 1, with a drying air velocity of 1.0 m/s, with which a final mass of 732.24 g was obtained with coffee moisture content of 12.0%, protein content of 11.7%, carbohydrate content of 21.7%, and free fatty acid content of 0.05%. Higher air velocities resulted in almost the same protein and carbohydrate content, as well as a fatty acid content of less than 0.1%, but a higher moisture content.

In this study, the thermal and hydraulic characteristics of the air flow over the metal shavings of the absorber of a solar air heating collector were analyzed. During the study, formulas were derived for calculating the temperature and hydrodynamic parameters of the flow. The air flow temperature, boundary layer thickness, local friction stress on the chip surface and other important parameters were determined. Calculations were performed for various flow rates and Reynolds numbers. The results obtained made it possible to evaluate the influence of metal shavings on the characteristics of the air flow. It was shown that the thickness of the boundary layer decreases with increasing Reynolds number, which is consistent with hydrodynamic theory. A comparison was also made of the thermal resistance for a smooth surface and a surface with metal shavings. The results showed that the use of metal chips could reduce the thermal resistance, which could be beneficial for improving the heat transfer efficiency in solar air heating collectors.

Stenter machines are used to remove moisture from fabrics produced in the textile industry. Following the drying process, the cooling process, which is applied to fabrics using injector channels, is conducted in the last section of a stenter machine, preventing fabrics from expanding and the degradation of their quality. The present study mainly aimed to investigate the fabric-cooling process in a stenter machine used actively in a textile company. First, industrial data were obtained with some experiments, and computational fluid dynamics (CFD) simulations were then conducted by validating the industrial data. All CFD models were simulated using ANSYS Fluent commercial CFD software. A total of four parameters, including two geometric and two operating parameters, were considered in order to investigate their effects on the fabric-cooling performance of the stenter machine. While the geometric parameters were the porosity (β) and injector angle (α), the operating parameters were the velocity of the airflow that cools the fabrics and fabric velocity, representing the movement of the fabric. As outputs of CFD simulations, fabric surface temperature values, the distributions of fabric surface temperatures, and some streamlines were illustrated. Although low values of porosity (β1 = 0.05) and injector angle (α1 = 0°) provided better performance, airflow velocity could be increased one or two times for the range of these constant parameters.

This paper entails an empirical and computational assessment of the air flow field in the close proximity of a vertically positioned radiant cooling panel. This radiant cooling solution differs from the conventional large-area radiant cooling systems (e.g., ceiling panels). It involves rather small-sized vertical panels positioned close to occupants. Moreover, the panels are designed so as to manage potential surface condensation of water vapor via integrated drainage elements. Hence, the panels can be operated with relatively low surface temperatures. The low panel surface temperature and its proximity to the occupants are intended to compensate for the potential lower cooling power due to the relatively small panel size. In this paper, we specifically explore the air flow field close to the local radiant cooling panel via laboratory measurements and CFD (Computational Fluid Dynamics). Thus, possible issues regarding discomfort due to draft and turbulence risk close to the radiant panel can be examined. To this end, a prototypical local radiant cooling panel was installed in a mock-up office room of a laboratory. During the experiments, the air flow speed was measured and simulated at several heights (between 10 and 110 cm from the floor) and distances (ranging from 1 to 50 cm from the radiant panel). The results allow for the evaluation of the draft discomfort risk as well as the reliability of CFD in reproduction of the measurement results. A further step involved the numeric analysis of the effect of the human model on the air flow patter.

The COVID-19 pandemic that hit Indonesia caused transition of the education process to online in 2020. The government seeks to improve the quality of student education in this pandemic era by preparing limited face-to-face learning. It is crucial to conduct a study on air because it is one of the mediums used to transfer viruses. This research took one sample of a classroom at SDN 27 North Pontianak. This research uses a Computational Fluid Dynamics simulation to display the air flow conditions of a room. The results showed that the fastest wind speed in the class ranged from 0.12 m/s to 0.44 m/s with green, yellow and red parameter color. The slowest wind speed was 0.01 m/s to 0.12 m/s with blue and green parameter color. The parameter shows levels are within limits suggested by ASHRAE and the effect of the availability of smooth air circulation for the classroom and stable air change. They were limiting the virus ability to spread by improving airflow. Rapid air exchange in the classroom lowers the risk of infection for students and teaching staff.

The subject matter of the article is the process of subsonic air intake shaping for gas-turbine engines at the airplane preliminarily design stage. The goal is to develop a mathematical model for non-circular air intake shaping for gas-turbine engines on the base of V. I. Polikovskii method of subsonic air intake shaping for high-bypass ratio turbofan. The tasks to be solved are: to consider the possibility of non-circular shape of the external outline of the engine nacelle; to take into account the possibility of non-circular shape of the internal air intake duct (in the first approximation, the shape of internal air intake duct cross-section is defined in the form of a rectangular with possible four different radiuses in its corners); to consider the engine inlet spinner presence. The methods used are: analytical and digital mathematical methods, implemented in MathCAD and Microsoft Visual Studio systems. The following results were obtained: On the base of the proposed method, new calculation module for the Power Unit software version 11.8 has been developed (С-language Win32 UNICODE application) having a friendly user interface. Conclusions. The scientific novelty of the results obtained is as follows: 1) mathematical model (algorithm and its program implementation) for non-circular air intake shaping for gas-turbine engines has been developed considering non-circular shape of the external outline of the engine nacelle, non-circular shape of the air intake duct internal outline, presence of engine inlet spinner, and zero expansion angle in the diffuser outlet cross-section; 2) adequacy of calculation results by the developed mathematical model is shown by means of comparison with the shape of real air intake, developed by the Antonov Company. For the following improvement of the mathematical model, it is desirable to add the possibility of considering S‑shape of the air intake duct, defining its length from designer’s considerations, defining a bigger radius of curvature of the air intake lip, and considering the presence of boundary layer bleeding devices in front of the air intake.

The subject matter of this article is the process of subsonic air intake shaping for high-bypass ratio turbofan at the airplane preliminarily designing stage. The goal was to improve a mathematical model of V. I. Polikovskii method of subsonic air intake shaping for high-bypass ratio turbofan. The tasks are to consider the presence of cant of inlet cross-section, required to perform effective operation at airplane cruising angle-of-attacks; to increase the radius of curvature of the air intake lip to provide air flow near it without flow separation, which was definitely determined and could not be increased in the existing method; to improve constant length velocity gradient law (used in this method) so that too large duct expansion angles near the air intake outlet cross-section can be avoided; to consider the engine inlet spinner presence. The methods used are analytical and digital mathematical methods, implemented in MathCAD and Microsoft Visual Studio systems. The following results were obtained: based on the proposed method, new calculation module for the Power Unit software version 11.8 has been developed (С-language Win32 UNICODE application) with a friendly user interface. Conclusions. The scientific novelty of the results obtained is as follows: 1) mathematical model (algorithm and its program implementation) for circular turbofan air intake shaping has been improved considering cant of the inlet cross-section, air intake lip rounding with two radiuses, presence of engine inlet spinner, and zero expansion angles in the diffuser outlet cross-section; 2) adequacy of calculation results using the improved mathematical model is shown using comparison with shapes of circular turbofan air intakes, developed by the leading aviation companies.

Air permeability is used to characterize textile fabrics with respect to their usability as a garment or filter, airbag or parachute. It depends on the fabric’s porosity, air voids in the fabric, yarn specifications, thickness and other parameters, making it hard to calculate it reliably from other parameters. At the same time, measuring air permeability requires relatively expensive and complex equipment that cannot simply be built by everybody. Here, we suggest a simple device, which can be built from inexpensive components and correlates air permeability to a time measurement. We show that these values are highly correlated with the results gained by the frequently used standard EN ISO 9237.

Air permeability is used to characterize textile fabrics with respect to their usability as a garment or filter, airbag or parachute. It depends on the fabric’s porosity, air voids in the fabric, yarn specifications, thickness and other parameters, making it hard to calculate it reliably from other parameters. At the same time, measuring air permeability requires relatively expensive and complex equipment that cannot simply be built by everybody. Here, we suggest a simple device, which can be built from inexpensive components and correlates air permeability to a time measurement. We show that these values are highly correlated with the results gained by the frequently used standard EN ISO 9237.

Air permeability is used to characterize textile fabrics with respect to their usability as a garment or filter, airbag or parachute. It depends on the fabric’s porosity, air voids in the fabric, yarn specifications, thickness and other parameters, making it hard to calculate it reliably from other parameters. At the same time, measuring air permeability requires relatively expensive and complex equipment that cannot simply be built by everybody. Here, we suggest a simple device, which can be built from inexpensive components and correlates air permeability to a time measurement. We show that these values are highly correlated with the results gained by the frequently used standard EN ISO 9237.

Research on battery thermal management systems (BTMSs) is particularly significant since the electric vehicle sector is growing in importance and because the batteries that power them have high operating temperature requirements. Among them, heat pipe (HP)-based battery thermal management systems have very high heat transfer performance but fall short in maintaining uniform temperature distribution. This study presented forced air cooling by an axial fan as a method of improving the cooling performance of flat heat pipes coupled with aluminum fins (FHPAFs) and investigated the impact of air velocity on the battery pack’s maximum temperature differential (ΔTmax). All experiments were conducted on lithium nickel manganese cobalt oxide (NMC) pouch battery cells with a 20 Ah capacity in seven series connections at room temperature, under forced and natural convection, at various air velocity values (12.7 m/s, 9.5 m/s, and 6.3 m/s), and with 1C, 2C, 3C, and 4C discharge rates. The results indicated that at the same air velocity, increasing the discharge rate increases the ΔTmax significantly. Forced convection has a higher ΔTmax than natural convection. The ΔTmax was reduced when the air velocity was increased during forced convection.

Due to the rapid growth of Erbil population and the resulting shortage of residential buildings, individuals actively utilized 5×20 m plots for two-bedroom residential houses. Consequently, poor, and unhealthy ventilation comes about. In this paper, the authors developed an old Barajeel (Wind Catchers) approach for natural ventilation. Two Barajeels (Wind Catchers) are designed and located at both extreme ends of the built unit. The two wind catchers are made as inlet and outlet for the air movement where the rate of air changes at its best. To validate the usage of the wind catchers a CFD Software was used to simulate the operation of the wind catchers for natural ventilations for average wind speed of 2 m/s. The results show a positive solution to solve the problem of the cramped such built units. It can be concluded that such solutions can be deployed by the local Kurdistan authorities.

The article presents current research results in the field of airflow through a façade with a width of 1 m and a height of 13.7 m and with a ventilated gap, and its effect on the year-round heat balance of this façade. An idea to influence airflow in the ventilated gap of the façade is presented based on the results of developed software and the suitability of closing the air gap in winter and in the transition period of the year is described. First, the boundary conditions of the calculations, which are further used in the energy balance between the interior of the building and the exterior environment are defined. In order to include these influences, a discrete analytical calculation was created. It consists of the time distribution of the investigated thermal phenomena calculations. A significant finding is an obvious benefit of controlling the airflow through a ventilated gap in the winter and especially in the transitional period of the year. This technological knowledge has a high potential for energy savings related to the heating of buildings. As the calculations show, airflow control through a ventilated façade reduces heat flow by 25–30% on average, and in contrast, it increases heat gains by 20% and the specific values are presented within the article.

Icing of the injection layer in underground tunnels and ventilation shafts leads to wear, destruction of supporting structures and flooding. In St. Petersburg the air temperature in winter can drop to -25 ° C, what can lead to these phenomena in the subway facilities. The article presents the modeling results of a viscous three-dimensional air flow, heat and mass transfer of a metro ventilation shaft in the Ansys CFX program. A numerical model of the ventilation shaft and the surrounding soil consisting of five layers has been developed: air; foam glass concrete; prefabricated cast-iron tubing lining; injection layer; soil massif. The parameters of the computational grid and the boundary conditions of the problem are specified. Two models of the ventilation shaft with an axial length of 1 m and 10 m were built. Temperature plots are constructed for three tasks, where the injection layer consists of water, wet clay soil and average between water and wet clay soil. The choice of overall thermal and technical characteristics of the thermal insulation material during the reconstruction of the existing ventilation shafts in three different sealing space conditions is confirmed.

Deficiencies in the drying and stacking methods of cocoa beans can be minimized by using a combination of both to improve quality. The purpose of this study was to obtain physicochemical and organoleptic quality information of dried cocoa beans produced by a combination of drying and stack drying. The treatments analyzed were drying 3, 8 and 16 hours followed by mechanical drying using an air flow of 0.05 m / s and 0.2 m / s at a temperature of 55 oC. As a control is only mechanical drying with two flow rates, up to a water content

The performance of porous carbon materials as sorbents is often compromised by the presence of humidity. Studying the kinetics of water vapour adsorption on activated carbons will undeniably help to overcome this issue. This has been approached in this work by evaluating the influence of several operational factors on the dynamic adsorption of water vapour in these materials. Specifically, different carbon types, particle sizes, air flows and ambient conditions (temperature and relative humidity (RH)) were systematically investigated. The impact of each isolated parameter on both the maximum water uptake and the uptake rate was analyzed by fitting the experimental data to the Linear Driving Force (LDF) kinetic model. The results show that except for the particle size, the studied variables play a role in the water sorption kinetics, although to a different extent. It was also confirmed that the LDF model can adequately describe the kinetics of water vapour adsorption independently of the experimental conditions. Finally, the complete water vapour adsorption process can be described by this model, obtaining a different value of the kinetic constant for the sequential stages, involving different adsorption mechanisms.

For the aircraft, the engine is its core component. Once the engine fails, the flight safety will be seriously affected; therefore, it is necessary to diagnose the failure in time. This paper briefly introduced three aircraft engine fault diagnosis algorithms based on support vector machine (SVM), random forest, and particle swarm optimization-back-propagation (PSO-BP) and carried out a simulation experiment on the performance of the three algorithms in MATLAB software. The results showed that the PSO-BP-based diagnosis algorithm had the highest recognition accuracy and the SVM-based diagnosis algorithm had the lowest, both for artificial fault data and real fault data. The PSO-BP-based diagnosis algorithm took the least average recognition time, and the SVM-based diagnosis algorithm took the longest time.

For the aircraft, the engine is its core component. Once the engine fails, the flight safety will be seriously affected; therefore, it is necessary to diagnose the failure in time. This paper briefly introduced three aircraft engine fault diagnosis algorithms based on support vector machine (SVM), random forest, and particle swarm optimization-back-propagation (PSO-BP) and carried out a simulation experiment on the performance of the three algorithms in MATLAB software. The results showed that the PSO-BPbased diagnosis algorithm had the highest recognition accuracy and the SVM-based diagnosis algorithm had the lowest, both for artificial fault data and real fault data. The PSO-BP-based diagnosis algorithm took the least average recognition time, and the SVM-based diagnosis algorithm took the longest time.

In this paper, a new calibration device for an air flow sensor of the VAV terminal unit is designed. Multi-aperture air outlets are designed to meet the calibration requirements of the air flow sensor in a variety of measurement range. The device can calibrate the air flow sensors of different types of VAV terminal unit by a movable flow rectifier without repeating the design of a different calibration pipeline. The Raspberry PI is used to design the high-performance GUI interface and controlling algorithm to achieve a one-button intelligent calibration. The air flow sensors in three different types of VAV terminal units are used to calibrate the experiment. After testing, the differential pressure value measured by the air flow sensor can accurately measure the air flow within the accuracy of 5% after the formula conversion. The conversion from differential pressure values to air flow values requires precise calibration in order to establish an accurate air flow equation, and here the calibration device plays a key role. The negative effect caused by the distance between the flow rectifiers and the VAV terminal unit is discovered. In other words, the distance between the inlet flow rectifier and the air inlet of VAV terminal unit should be kept as close as possible, or within a range of 2~3 cm. Moreover, the distance between the air outlet of VAV terminal unit and the middle-flow rectifier should be kept as close as possible; otherwise, any slight gap will cause a huge error in the calibration result. The research contributes to the further study of airflow sensing technology through the conversion and calibration of differential pressure measurements to accurate air flow values.

Fluid flow around bluff bodies occurs in numerous fields of science and engineering, such as flows pass vehicles, cables, towers and bridges. These flows have been studied experimentally and numerically for the last several decades. The investigation of flow around high-speed trains is an important application of bluff bodies. Fluid flow, aerodynamic forces and moments, separation and wake region have been studied for the last several decades. This paper brings together a comprehensive review of the research on air flow around high-speed trains and their impacts.

Mashrabiya had formed one of the most important elements of architecture specially civil architecture in Islamic heritage. As it is known as a successful architectural solution for climate nature because the shape of its configuration allows it to control sun rays and air currents and forming interior comfortable environment and also providing privacy specially in housing architecture. So Mashrabiya comes in our Islamic heritage with consistency with climate, privacy and culture considerations for the occupants of the interior environment additionally with Aesthetic considerations represented from its infinite design characterized with the elasticity of its formations. The Egyptian carpenter was one of the most handicrafts men who represented Mashrabiya arts with different designs and forms and he excelled at perfection at this kind of art and he represented it to the whole world in the form of beautiful wooden interfaces. Many International architects paid attention to this important architectural element and started taking inspiration from this concept to represent modern solutions for many architectural interface for public and private buildings and they turned this wooden local heritage element to elastic system for natural light responding to high technology and representing Contemporary aesthetic solutions taking its origins from Islamic heritage in consistency with modernization and Contemporary Technology.

The screenless centrifugal fractionation approach is offered for the fractionation of the long-stalked agricultural materials lengthways. The screenless centrifugal fractionation device and its analytical model are described. The basic processes are specified – accelerating particles with the centrifugal disc, spreading in the annular aerodynamic channel, and assorting with the partitioning cylinders. The mathematical simulation of the particle acceleration with the centrifugal disc and the dropped particles motion in the unward airflow processes is carried out. The computer-based experiment is conducted. Paths of particles in the annular aerodynamic channel are obtained. The paths differ so greatly that it is possible to state the separating properties of the centrifugal force field and airflow combination. The recommendations on the arrangement of the partitioning cylinders are given. The simulation results imply the feasibility of assorting the long-stalked materials with the centrifugal tool at the cost of the differences in particle spreading paths in the airflow.

Drying grass fodder in Europe’s Alpine countries is becoming increasingly important due to positive effects on the fatty acid composition of milk. A proper approach and technology of fodder drying can raise its quality to the level of grass silage. In principle, drying fodder means extracting water from fodder by means of ventilation – the air, the key to the speed of drying. Besides low relative air humidity, its flow rate through the fodder is also important. In the literature, the lower- and upper-bound limits of air flow rates can be found, with a difference of 85 % between the two. The article describes a test, measuring energy consumption and the efficiency of drying at a low air flow, often used in practice, and a high air flow. It was found that a high air flow results in 38 % higher energy consumption per kilogramme of extracted water, compared to a low air flow. The executed test has proved that drying at a higher air flow will not have a proportionally greater effect.

The article presents an improved experimental-theoretical method for calculating the particle trajectory in a pneumatic separating channel. Mathematic simulation of the velocity field of the air flow in the longitudinal-vertical plane of the pneumatic separating channel is made on the basis of measuring their actual magnitude and direction at the nominal grain load. Calculation and construction of particle trajectories is performed with regard to their ricochet from the channel walls. The improved method includes three stages. At the first stage, the vector field of airflow velocity in equal rectangular centers located in the separation area throughout the height and depth of the pneumatic separating channel are determined experimentally. At the second stage, on the basis of particular values of velocity vectors in the rectangular centers the systems of math equations are made. They describe the vertical and horizontal components of these velocities in the corresponding sectors of coordinate axes. At the third stage, the system of differential equations of particle motion in a pneumatic separating channel relative to a Cartesian coordinate system is made and their trajectories are calculated. This improved method raises the accuracy of calculation the particle trajectory inside the pneumatic separating channel and aerodynamic parameters of particles when leaving it. It results in speeding up the process of optimization of the design parameters of the channel and the attached elements of the pneumatic system.

Professional oral hygiene is fundamental to prevent peri-implant disease. Appropriate instruments should be used in patients with restorations supported by dental implants: they should be effective in deposits removal without damaging the implant components surface. The aim of the present study is to investigate and summarize the results regarding the efficacy of oral hygiene techniques described in the literature in the last 10 years in patients rehabilitated with dental implants not affected by perimplantitis. The present systematic review was conducted according to guidelines reported in the indications of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA). The focused question was: “Which are the most effective instruments for professional oral hygiene on implants not affected by perimplantitis?”. The initial database search yielded a total of 934 entries found in PubMed®/MEDLINE and Cochrane Library. After full text review and application of the eligibility criteria, the final selection consisted of 19 articles. The risk of bias of included studies was assessed using the Newcastle Ottawa scale (NOS) and the Cochrane Handbook for Systematic Reviews of Interventions. Curette, scalers and air polishing were the devices most frequently investigated in the included studies. In particular, glycine powder air polishing appeared to be significantly effective in reducing peri-implant inflammation and plaque around implants. The application of the more recent erythritol powder air polishing also yielded good clinical outcomes. Further studies are needed to improve the knowledge on the topic in order to develop standardized protocols and understand the specific indications for different types of implant-supported rehabilitations.

Dissipative splitter silencers are widely used in industry for the reduction of propagated sound waves in ducts. Even though these systems are effective from the acoustics point of view when they are properly designed, they also introduce a pressure loss in the system, due to the modification of the properties of the flow circulating inside the duct. This effect is not desired in some industrial applications, so it is necessary to be able to predict the pressure loss as precisely as possible to design silencers according to the needs. Nevertheless, the prediction made by standards are usually limited to given geometries or flow speed. In this work, we present a comparative study on the results obtained for the pressure loss by means of the standards ISO 14163 and VDI 1801-1, numerical simulations with the finite element method, and experimental measurements. Additionally, two different profile shapes and four input face velocities are tested in order to know the influence of these parameters in the variations of the flow and the accuracy of the prediction of the different methods.

Monitoring of Tribolium castaneum, the red flour beetle, involves the use of aggregation pheromone 4,8- dimethyldecanal (4,8 DMD) and kairomones such as cereal oils. Despite their present use, certain information which maximizes the efficacy of these compounds is still lacking. These experiments tested the effects of distance from the pheromone and edible oils on the orientation of T. castaneum adults. The movement of adults toward the aggregation pheromone was determined by changing the distance from the pheromone or the air flow. The adults released inside a glass apparatus tested their orientation either toward the food oils or the empty vial. The maximum trap catch was recorded at distances up to 60 cm from the pheromone and with the presence of air flow. The oils having botanical origin successfully attracted adults than those of animal origin. It is concluded that the orientation of T. castaneum adults varies with the distance from pheromone, air flow and the nature of food oil.

Solar drying using greenhouse dryers is a viable method from the technical, economic, and environmental perspectives, allowing the drying of agricultural products for conservation purposes in different regions of the world. In Colombia, the drying of aromatic plants such as mint (Mentha spicata) is usually done directly and in open fields, which exposes the product to contamination and loss of quality. Therefore, the objective of this research was to use a three-dimensional computational fluid dynamics (CFD-3D) model previously successfully validated and implemented in this work to study the performance of air flow patterns, temperature, and humidity inside four greenhouse-type dryers contemplated for a region with hot and humid climatic conditions. The results found allowed us to observe that the spatial distribution of temperature and relative humidity are related to the air flows generated inside each dryer, therefore, there were differences of up to 7.91 °C and 23.81% for the same evaluated scenario. The study also allowed us to conclude that the CFD methodology is an agile and precise tool that allows us to evaluate prototypes that have not been built to real scale, which allows us to generate useful information for decision-making regarding the best prototype to build under a specific climate condition.

ABSTRACT: This study aim to develop a system, called FANS-N, for evaluation the exhaust fans in the ventilation system of broiler facilities. The system is divided into: 1) Mechanical Structure - consisting of two stepper motors for positioning a anemometer sensor in the vertical and horizontal coordinates; 2) Electronic Interface - control of the anemometer positioning and record data of wind speed; 3) Control Programming Module – accountable for the cursor movement, measurement and record the wind speed data with the anemometer at predetermined points; and 4) Analysis Programming Module - responsible for the interpretation of wind speed values at each point. The software uses artificial neural networks (Multi-Layer Perceptron) for images analyses of data base. The output of neural network give to the user the following recommendations: "possible changing", "maintenance", "standard limit", and "within standard". The system was able to evaluate the exhaust fans, identify the failures and proposing solutions to farmers of a preventive diagnosis.

The paper deals with problems of impact of air flow in ventilated insulating air layer of the external wall on behaviour of thermal-technical parameters of the proposed external structure (according principles of STN 73 0549, which is not valid now), by comparing them in the calculation according to the valid STN standards, where air flow in the ventilated air layer is not taken into account, as well as by comparing them with behavior of thermal-technical parameters in the proposal of sandwich external wall with the contact heat insulation system without air cavity.

Purpose. The scientific paper highlights research of aerodynamic pressure and distribution of airflow velocity field along the moving high-speed train. Methodology. The study of velocity field distribution around the moving high-speed train is produced by simulating its movement as axially symmetric body with the ogive-shaped head and tail parts in compressible (acoustic) environment. Findings. The values of the absolute velocity (theoretical) of air flow generated by the body movement is determined (for the case when the body moves at a constant speed (200, 250, 350, 400 km / h) at a certain height from the ground), for the points located at different distances from the axis of the moving body (high-speed train). The calculations results allowed building the graphs of the air flow velocity in the acoustic environment along the moving body at different distances from it. Using the Bernoulli law (pressure change dependences on the flow velocity), the values of the overpressure generated by the air stream from the moving body were determined. Originality. This is the first theoretical study of the aerodynamics of the high-speed train as axially symmetric body with the ogive-shaped head and tail parts in compressible (acoustic) environment, moving with steady speed. The research results allow us to establish the distribution of the excess air flow pressure generated along the moving high-speed train. Practical value. The obtained results allows determining of the following parameters: 1) requirements for physical-mechanical and strength characteristics of the individual elements of the railway infrastructure in the areas of high-speed train movement, subject to aerodynamic pressure; 2) minimum distance from the track safe for people location during high-speed train passage.

This study presents a detailed methodology for non-intrusive measurement of cooling air mass flow rate that enables an overall machine evaluation. This approach enables the simultaneous measurement of air mass flow with shaft torque at differing operating points while minimising the change in air flow introduced by the measurement system. The impact of geometric parameters in the designed system is investigated using a detailed 180° computational fluid dynamics (CFD) model. Special attention was paid to minimising their influence on pressure drop, the mass flow rate through the machine, and measurement uncertainty. Based on the results of this investigation, the system was designed and manufactured, and the experimentally measured data was used to validate the CFD predictions. For the as optimal identified configuration, the flow rate is predicted to decrease by 2.2% relative to unrestricted operation. The achieved measurement uncertainty is ± 2.6% at synchronous speed.

The aerodynamic noise generated from a perforated metal plate varied by air-flow direction. In the case of expansion type perforated metal plate, it generates very large level aerodynamic noise with a prominent peak in the frequency characteristic. In this paper, velocity fluctuation at some measuring points is measured by a hotwire anemometer to examine its cause. In the experiment, coherent output power (COP) of velocity fluctuation is calculated. The coherence function is defined by the relations between the generated noise and velocity fluctuation of air flow behind perforated metal plate. The expansion type perforated metal plate generates orderly vortex shedding and it brings the vibration of perforated metal plate. The distribution of partial overall value of COP indicates strong correlation with the plate vibration mode. That phenomenon is predicted as lock-in phenomenon between vortex and vibration of the plate.

All companies aim to produce the best quality product and receive the highest profit. Also ensuring a healthy environment for employees is of high importance. Choosing the right type of spray booth will assure the latter in any company that is involved in painting. The article reviews and evaluates different airflow type spray booths. Using analysis of options the optimal decision is determined taking into account the price, simplicity of construction, paint finish quality, general spray booth size and energy consumption.

Centrifugal fan in series is the core facility for pneumatic transportation. Its operation is required to be adjusted real time as the flow rate of transported materials changes. For optimisation performance, internal flow of a type 700 three-stage fan at rated rotation speed is analysed with FLUENT6.3 for various total pressure. Multiple reference frame (MRF) model is used for the impellers rotation in simulation, and Re-Normalisation group (RNG) κ-ɛ turbulence model and Roe-FDS flux type with first-order upwind difference scheme are used for calculation of compressible flow under various total pressure. Flow characteristics are obtained and differences of total pressure and velocity distribution in every impeller are analysed in different conditions, and velocity distribution on meridian plane as well as section of wind guide plates and volute are compared. Results show that there are many vortexes and backflows in fan with higher total pressure, and the lower pressure, the more smoothly flows, besides flow at inlet and outlet of impellers and in guide plates is seriously influenced by total pressure. Curves of P-Q and P-η at 4600 r/min are predicted based on simulation, which is helpful reducing the impact caused by off-design operation and improving efficiency.

Typically, the actual volume of the residual limb changes over time. This causes the prosthesis to not fit, and then pain and skin disease. In this study, a prosthetic socket was developed to compensate for the volume change of the residual limb. Using an inflatable air bladder, the proposed socket monitors the pressure in the socket and keeps the pressure distribution uniform and constant while walking. The socket has three air bladders on anterior and posterior tibia areas, a latching type 3-way pneumatic valve and a portable control device. In the paper, the mechanical properties of the air bladder were investigated, and the electromagnetic analysis was performed to design the pneumatic valve. The controller is based on a hysteresis control algorithm with a closed loop, which keeps the pressure in the socket close to the initial set point over a long period of time. In experiments, the proposed prosthesis was tested through the gait simulator that can imitate a human’s gait cycle. The active volume compensation of the socket was successfully verified during repetitive gait cycle using the weight loads of 50, 70, and 90 kg and the residual limb model with a variety of volumes. It was confirmed that the pressure of the residual limb recovered to the initial state through the active control. The pressure inside the socket had a steady state error of less than 0.75% even if the volume of the residual limb was changed from −7% to +7%.

In order to evaluate the influence of the texture characteristics of agricultural nets on the air flow passing through them, a micro wind tunnel was designed and built in the testing and engineering laboratory of Sachim s.r.l., an Italian high-density polyethylene (HDPE) technical textiles manufacturer. The micro wind tunnel (0.1345 m diameter) allowed the simultaneous measurement of the air flowrate and the pressure drop through a net sample. The equipment was designed to set up the inclination of the net samples with respect of the airflow at fixed angles (90°, 60°, 45°, 30°). The variation of the pressure drop with the air velocity on four different flat woven round monofilament HDPE nets perpendicular to the air flow are here reported. In all cases the air velocity measured into the micro wind tunnel was above 4 m s–1 hence reported results do not consider low wind speed. Preliminarily, the loss coefficient was assumed as a function of porosity and Reynolds number, calculated with reference to the equivalent diameter of the pores, FS(Rel,ε) and showed percent deviations form experimental results in the range 14.6%÷25.3%. Hence a simplified expression of the loss coefficient, depending only on the porosity was proposed, FS(ε) which highlighted differences with experimental results in the range 3.5%÷20.3%. Finally, results were compared with those based on the Bernoulli’s principle found in the literature.

This paper presents the research of interaction of air flow and melted material in production of fibrous materials. Correlations for calculation of air flow rate in different cross sections of a stream are acquired. The developed method of calculation of air flow rate at point of contact with stream of the melted polymeric material can be used in construction of blow heads models with a slot nozzle in production of fibrous products from different polymeric materials.

Conducting of theoretical investigations of moving process of grain heap under the action of air flow and analysis of obtained trajectories of moving is necessary at design of pneumo-separating devices of grain-cleaning machines. There are two variants of calculation of moving trajectories of components: taking into account of interaction between particles and without this interaction. The aim of the given study was comparison of both variants of accounting. Process of moving of grain heap components is considered on the example of suction chamber of machine for preliminary grain cleaning MPZ-50. By results of analysis of obtained moving trajectories of grain heap components it is established that resistance force of material layer reduces shift of moving trajectories of grain heap components toward channel of main cleaning (0.005…0.007 m). Light impurities with the factor of a sail-kП=1.09 m-1 with initial conditions of particles entering the receiving chamber in x0=0 -0.025...0 m under the action of lateral air flow is removed from the separation zone through the channel in the sedimentary pre-treatment chamber of the pneumatic system of the machine MPZ -50, and impurity at x0=-0.050 m fall on the outer wall of the main channel clean and under the action of gravity slide down into grooves of the supply roller on top of the full grain, which increases the probability of their selection in the main channel clean. As to usage of first or second variant of calculation of moving trajectories than the conclusion may be accepted that for preliminary calculation of pneumo-separating devices for example, determination of location of their working parts, it is enough to consider moving process of grain heap components without accounting of resistance force of material layer that allow to simplify similar investigation significantly. Conducting of theoretic investigations with accounting of resistance force is necessary for determination of optimal parameters of working organs.

This paper aims to examine the influence of aerodynamic forces acting on the Siemens Desiro railcar, and the percentage of these forces in the total values of resistance to motion. In this regard the numerical simulation of the airflow is used as a method of analysis. We started from the 3D geometric model at a scale of 1:1 of the vehicle bodywork constructive form. The air flow simulation is performed taking into account the speed limits of the vehicle namely 0 km/ h and 140 km/ h, interval in which eight point values are chosen.